Dental implant



April 25, 1944. E. J. KREssE DENTAL IMPLANT Filed March ll, 1943 EDwARJ. KRESSE INVENTOR.

` @ta/w57! Patented Apr. 25, 2.9214

UNITED STATES PATENT QFFICE DENTAL IMPLANT Edward J. Kresse, Denver,Colo.

Application March 11. 1943, Serial No. 478,823

4 Claims.

This invention relates, in general, to dentistry and has reference moreparticularly to improvements in materials from which to manufactureimplants for use in mounting articial teeth, but which can also be usedin traumatic bone surgery.

It has long been the custom to mount crowns on the natural roots whichhave iirst been prepared by grinding, cleaning and filling according toan established asceptic surgical procedure. Such practice has beenlargely discontinued for reasons that will not be pointed out herein.

As early as 1909 the use of a peculiarly constructed metal frame forinsertion into the alveolus of an extracted tooth or in a cavity drilledin the jaw bone, was suggested as a bearing for` an artificial tooth(Patent 943,113). Since that time a large number of experiments havebeen carried out which show that implants for the mounting of crowns andfor bone surgery are likely to cause sepsis and necrosis unless thematerial employed is selected with great care.

A metallic alloy sold under the name of Vitallium and composed of 65%cobalt, 30% chromium and 5% molybdenum has been found to be a suitablematerial for implants as it does not set up any appreciable electrolyticaction which, if present, is objectionable as it produces metallic saltsin the local tissue iluid which causes excessive cellular proliferationand in general inhibits osteoblastlc activity.

It is the object of this invention to produce a suitable nonmetallicmaterial for use in makin surgical implants that will not produce anyelectrolytic action and in the body of which certain germicides can beincorporated which will be released graduallv through osmotic action,and in suilicient quantity to inhibit sepsis and necrosis.

It has been found that certain plastic substances, such, for example, asmethyl methacrylate. polymers when mixed with a germlcide have osmoticproperties which allow the germicide to slowly pass out in suiilcientquantity to inhibit sepsis. Such implants keep tissues and surroundingbone clean and healthy, thereby permitting full osteoblastic activityand osteogenesis to proceed in' a normal way.

Another object is to vproduce an implant that shall be provided with adrainage opening extending the entire length and through which iluidsfrom the bottom of the alveolus can escape.

A further object is to produce an implant with means for making anoperative connection with a tool for rotating it when it is inserted.

The above and any other objects that may berial, such as stainlesssteel, gold or silver.

come apparent as the description proceeds are u attained by means of aconstruction and an arrangement of parts that will now be described indetail, and for this purpose reference will new be had to theaccompanying drawing in which:

Figure 1 is a cross section through an upper jaw bone showing an implantin place therein;

Figure 2 is a side elevation of the implant;

Figure 3 is an end view of Figure 2;

Figure 4 is a longitudinally diametrical section taken of Figure 3;

Figure 5 is a fragmentary diametrical section to an enlarged scale; and

Figure 6 is a longitudinal section similar to that shown in Figure 4 andshows a slightly modiiled construction.

In the drawing reference numeral 5 designates the jaw bone and 6 theeshy covering thereof, while reference numeral I designates the implantand 8 a crown secured to the implant.

In order to illustrate one speciiic use of the material that forms thesubject of this invention a dental implant constructed therefrom will bedescribed. 'I'he material is a plastic in the poly. mer or monomer ofwhich a chemical having germicidal properties or actions has beenincorporated in a manner which will hereinafter be referred to ingreater detail. The plastic which has been employed in this inventionand which is illustrative of plastics of a type suitable for thispurpose is a methyl methacrylate which is furnished by the manufacturerin two parts, one of which is a powder and the other a liquid monomer,such plastics are thermoplastic and can be molded in a suitable metalmold. In the present instance, a two-part mold has been employed.

'I'he implant has the general appearance of a wood screwland in thedrawing the threads have been designated by reference numeral 9. Duringthe molding operation the implant is provided with a drainage openingIII that extends the entire length thereof and may be formed by atubular metal member such as that designated by reference numeral l I,although if plastics of sufcient hardness are used, such openings may beformed in the plastic implant itself. The larger end of the implant isprovided with a ferrule l2 which is made from some noncorrodible mate-In order to turn the implant during the operation of inserting it in thealveolus, it is provided in addition to the drainage tube I i, with oneor more short tubes i3 that are placed adjacent the drainage tube andsoldered or welded thereto or they may be secured to the drainage tubeby a wire wrapping as it is only necessary that they be held in positionduring the molding operation since after the plastic has set, it willsecurely hold the several tubes in position.

Since the process of molding plastics is well understood. it will not bedescribed herein. In the present case it merely involves a two-part moldhaving an opening of the size and shape desired. When the materialsforming the plastic are mixed, certain chemicals having germicidalproperties such as silver nitrate, iodine crystals, thymol iodide, sulfaderivatives, formalin derivatives, either in the form of a fine powderof uniform of varying size, or as a liquid are mixed with the monomerand after the plastic has been molded and set, such germicldes arequiteuniformly distributedthroughout the entire mass. The presence of thesegermicides produce a plastic that has osmotic properties and thereforewhen the implant is in position the fluids from the socket graduallyabsorb sumcient quantities of germicide to inhibit sepsis or necrosis.

The method of inserting the implants is that after the tooth has beenextracted, a suitable tap is employed for cutting threads in the wallsof the alveolus, after which the implant is positioned on the end of atool I4, having a plurality of prongs I5 positioned to engage in theopenings in tubes II and I3. The tool I4 forms what may be termed ascrew driver and enables the operator to place the implant in position.After the implant has been positioned in the alveolus, the tool isremoved, leaving the central drain opening I free to permit the escapeof fluids and in this way the production of pressures at the bottom ofthe alveolus is prevented. The germicides that have been incorporated inthe plastic prevent sepsis and promote osteoblastic acitivity and thenew bone thus formed' lls the grooves between the threads and provide afirm and rigid support for the implant.

For the purpose of hastening and expediting the osmotic process foreignobjects such as fine particles of rubber of the type employed invulcanized dentures may be mixed with the polymer or monomer before thematerials are molded and this produces a plastic body of such porosityas may be desired. These have been indicated by dots in the sections andhave been designated by numeral I6. However, when germicides of crystalsform are employed, these will leave pores of microscopic size as theydissolve, thereby providing a multitude of passages that graduallyextend inwardly and through which the germicide is liberated in sumcientquantity to prevent sepsis. Increased porosity may also be obtained byother means such as mixing other than'the normal monomer with thepolymer or mixing organic plastics therewith, and it may also beobtained in the fabrication of the plastic by other chemical or physicaltreatments.

After the implant has been positioned and the new bone growth has formedso as to hold it rigidly and after all danger of irritation anddecomposition has passed, a crown I3 may be attached by mean/s of prongssuch as those indicated by reference numeral I5 in Figure 4.

From the above description it will be apparent that the implant that hasbeen described and which is illustrative of surgical implants made fromthe material that forms the subject of this invention is: first of all,a nonmetallic implant, and since the material is a nonconductor ofelectricity and is of uniform composition, it cannot produceelectrolysis. Another important feature of distinction is that itcomprises in its'body a 75 material having germicidaproperties whichproduce porosity and which gives to the material osmotic characteristicsthat permit the germicide to be slowly delivered to the enclosingmembranes; this a property that is not present in metallic implants. Theamount of porosity can be regulated in the manner above pointed out.

Although the implant which forms the subject of this invention has beendescribed in connection with dentistry, it is also equally suited foruse in traumatic bone surgery where ordinary metal implants oftenproduce necrosis. The shape of the implant and the size, shape and pitchof the threads, can, of course, be varied as`well as its size and sincethe material of which it is formed is very strong, it is highly suitablefor connecting pieces of bone that have been broken because theproperties that make it suitable for dental implants are of equal valuewherever implants are indicated in connection with any other portion ofthe body.

It is to be understood that any suitable plastics can be employed,either thermosetting or thermoplastic.

TheA roots of the teeth are separated from the jaw bone by a layer ofperidontal tissue which is elastic and serves to absorb shock. In Figure6 an enlarged sectional view of the assembly is shown in which thecenter dowel'pin I5 is shown as extending almost entirely through theentire length of the drain tube II, or through the opening where nodrain tube is used. Between the dowels I5 and the sides of the tube anelastic cement I1 is positioned and a layer of this cement is positionedbetween the tooth 8 and the implant as shown at I8. The elastic cementmay be of natural rubber, a synthetic rubber or plastic and serves thedouble purpose of securing the tooth to the implant and as a shockabsorber corresponding in function to the peridontal tissues. Instead ofhaving the elastic connection in the implant the dowels may be mountedelastically in the tooth.

Having described the invention what is claimed as new is:

1. A material for'use in making surgical implants comprising athermoplastic of the methyl methacrylate type having incorporatedtherein a solid water soluble chemical having germicidal properties, thechemical being present in sufficient quantity to produce a porousstructure after the germicide has been dissolved and removed by osmoticaction.

2. A material for use in making surgical irnplants comprising methylmethacrylate and a water soluble germicide` chemical in crystal form.the latter being present in the implant in sufcient quantity to producecontinuous, inwardly extending passages as the germicide is dissolved.

3. A material for use in making surgical implants comprising athermoplastic of the methyl methacrylate type with which is mixedparticles of dental vulcanite in sufilcient quantity to produce a porousstructure, and a water soluble chemical having germicidal properties.

4. A non-metallic material for use in making surgical implantscomprising a thermo responsive plastic, free from rubber, in which isincorporated a germicidal chemical in crystal form, the crystals beingpresent in suiiicient quantity to produce continuous passages as thechemical dissolve whereby the germicide will be slowly dissolved andreleased when subjected to the action of body iiuids.

EDWARD J. KRESSE.

